Room temperature vulcanizable organopolysiloxanes are well known articles of commerce. In general room temperature vulcanizable organopolysiloxane compositions include the two-component systems, in which the compositions cure spontaneously after mixing the components and the one-component systems which cure in the presence of moisture, oxygen or some other material to form elastomers.
The one-component RTV organopolysiloxane compositions known heretofore are prepared by mixing diorganopolysiloxanes having terminal reactive groups, such as hydroxyl and alkoxy groups with amine-substituted organosilicon compounds in which the amine groups are bonded to silicon through Si--N linkages.
In certain industrial applications, these one-component amine-containing organopolysiloxanes have certain disadvantages. For example, the amine-containing organopolysiloxanes form a skin on the surface of the material on exposure to atmospheric moisture. The formation of the skin on the surface of an otherwise uncured room temperature vulcanizable composition impedes the cure of the material under the skin, thus making it difficult to further process the material as is frequently required and produces poor adhesion of the resultant silicone elastomer to a substrate.
Furthermore, amine-containing organopolysiloxane compositions which utilize amine-substituted silicon compounds containing aliphatic amines as cross-linking agents have a very limited "pot-life" once the composition has been exposed to atmospheric moisture. In many industrial applications it is essential that the composition have a long "pot-life, but once applied, a rapid cure with good adhesion are essential requirements.
U.S. Pat. No. 4,170,700 to Sweet describes a method for accelerating the surface curing of room temperature vulcanizable compositions by exposing a composition containing hydroxyl terminated organopolysiloxanes and amine-substituted silicon compounds to atmospheric moisture and carbon dioxide in excess of that present in the atmosphere.
U.S. Pat. No. 3,923,736 to Nitzsche et al describes room-temperature vulcanizable organopolysiloxane compositions having a long "pot-life" which contain diorganopolysiloxanes having terminal groups capable of condensing with an amine-substituted organosilicon compound containing at least three silicon bonded amine groups per molecule having the formula .dbd.NCH(CH.sub.3 (C.sub.2 H.sub.5.
Generally, it has been found that when the amine-containing organopolysiloxanes are exposed to carbon dioxide and moisture to accelerate surface curing, the resultant elastomer does not exhibit good adhesion.
It is therefore, an object of the present invention to provide a method for improving the adhesion of an organopolysiloxane composition to a substrate. Another object of the present invention is to provide a method for improving the adhesion of an organopolysiloxane composition containing an amine-substituted silicon compound as a cross-linking agent. A further object of the present invention is to provide a method for preparing a silicone elastomer having a smooth, glossy surface.